Skype's international growth engenders these two chicken-and-egg questions

Telecom research firm TeleGeography says that about half of Skype's voice traffic is international. We're talking about about 4.4 percent of all the 264 billion global minutes carried on VoIP as well as circuit-switched lines.

Parsing the numbers further, we see that Skype's portion of all global phone minutes increased from 2.9 percent of such traffic in 2005 to the 4.4 percent I cited this year.

Other VoIP service's shares of minutes jumped from 16.6 percent in 2005 to nearly 20 percent this year.

There's one observation that jumps out at me, but that observation doesn't lead so much to a conclusion as to a question.

Obviously, the rate of Skype's growth in international voice is outpacing other VoIP, and is gaining percentage and traction in the overall international voice market.

But at least to me, that prompts two "chicken-and-egg questions":

How many Skype calls are made just because the participant(s)- on either or both ends of the call- have Skype? In short, "hey, Skype is cheap, we haven't talked to cousin Marie in Paris for awhile..let's give her a call, OK?"

Second, how many of these calls would not have been made if the participant(s) did not have Skype at the ready?

Does the mere presence of Skype on your desktop or other device inspire the urge to call internationally, rather than service an existing desire to do so at a given place and time?